Where a person negotiates or transfers a document of title for value otherwise than as a mere intermediary under the next following section (Section 36-7-508), then unless otherwise agreed he warrants to his immediate purchaser only in addition to any warranty made in selling the goods

1. (a) that the document is genuine; and
2. (b) that he has no knowledge of any fact which would impair its validity or worth; and
3. (c) that his negotiation or transfer is rightful and fully effective with respect to the title to the document and the goods it represents.